A research program has been established to develop and evaluate a short term days to weeks) pneumatic ventricular assist pump and a long-term (>two year) replantable electric ventricular assist pump. The program has focused on a close interaction and cooperation between a dedicated group of physicians, engineers, veterinarians and technical personnel. The pneumatic assist pump, designed and built in our laboratories and first used in the clinical setting at our University Hospital in 1976, will be employed in patients with acute heart failure following open heart operations and as a "bridge" for transplantation. Specific attention will be directed toward the evaluation of alternate valving systems and improved pump inflow cannulas in animal implant studies. Clinical use of the assist pump will continue with attention directed to appropriate indications for use, role of biventricular support, role of anticoagulants and antiplatelet drugs, and on long-term results. Certain patients with irreversible, end-stage left ventricular failure require long-term left ventricular support. An implantable, electrically powered, assist pump has been under development for the treatment of such patients. A compact, custom designed, brushless DC motor is used to rotate the nut of a highly efficient long-life roller screw, thus converting electrical energy to actuate the pusher plate of a blood pump. A prototype system with external electronics and transcutaneous (wireless) energy transmission has been evaluated in animal studies. We now propose to employ a completely implantable system. Detailed engineering analysis will be performed to evaluate flow patterns, system performance, and control mechanisms. The motor-driven left ventricular assist pump will be implanted in normal animals and those with profound left ventricular failure. We will study the physiologic effects of assist pumping, the host-prosthetic pump interaction, and the system reliability. Our goal of this phase of the assist pump program is to complete the engineering and physiologic testing proposed by NIH and required by FDA to begin initial patient use at the completion of the proposed grant period.